Sports illustrated issues from January 7, 1958 to March 8, 1959, inclusive, did not have their copyrights renewed. This photo was taken by staff photographer John G. Zimmerman and was a work for hire, so the copyright was owned by the magazine and entered the public domain when the copyright was not renewed in 1986.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
Uploaded a work by A. Y. Owens for LIFE from [https://vault.si.com/vault/1958/08/18/41427 Sports illustrated. Vol. 9, no. 7, August 18, 1958] with UploadWizard